Some known steering column assemblies are configured such that when a driver rotates a steering wheel in a desired direction, a steering column shaft connected to the steering wheel is rotated, and an intermediate shaft transmits the rotary force of the steering shaft through a universal joint to a gear box, which may include a rack and pinion gear.
The gear box converts the rotational motion of the steering shaft into a rectilinear motion by the rack and pinion gear, and transmits the rectilinear motion to a rack bar. As such, the rack bar transmits the force to a tie rod connected to a tire knuckle such that the driving direction of the vehicle can be changed.
Some steering column assemblies utilize upper and lower bearings to rotatably support shafts within a steering column jacket. In some assemblies, a third bearing is added and/or a steering column structure is enhanced to achieve a required noise, vibration, harshness (NVH) and/or stiffness performance. However, a third bearing may cause undesirable high and low turning torque. However, assemblies without a third bearing or enhanced structure may experience increased noise and vibration generation and allow contaminants into the steering column assemblies. Accordingly, it is desirable to provide a steering column assembly with improved dampening, NVH, stiffness, and sealing performance, without causing undesirable high or low turning torque.